sender

[toraj58]

sender is object that triggered the event.

for example you can have only one event handler for more than one controls.

consider this example:

        private void Form1_Load(object sender, EventArgs e)
        {
            button1.Click += new EventHandler(Btn_click);
            button2.Click += new EventHandler(Btn_click);
        }

        private void Btn_click(object sender, EventArgs e)
        {
            Button btn = (Button)sender;

            MessageBox.Show(btn.Text);
        
        }

Explanation: before running the above code add two button control to your main form and let the name properties of them be : button1 and button2.

then in form load event i attached single event handler function (Btn_click) to both of their click events.

if button1 trigger the event MessageBox will show its text property that is button1; if button2 trigger it MessageBox will show text property of second button.

Notice that sender is type of Object so i casted it to Button to extract the text property.